Psychological effects of colour
This is a bright cheerful colour closely related to the sun. Especially on dull grey days it will cheer you up, makes you more mentally alert and enthusiastic. Too much and too bright yellow make induce restlessness and freak you out.
Orange is quite a stimulating colour, related to action and vitality, but when used excessively it may induce restlessness like yellow.
Very stimulating, and excites the brain. Also related with alertness, vitality and excitement and in a negative way with aggression and violence. A darker red invokes feelings of richness (the "red pluche", royalty and the church) and reverence. The brighter version has "amorous connotations".
When used in full or near-full chroma, purple is another colour inducing the impression of richness and reverence. The other side of the medal is instability and uneasiness, as some countries relate this colour to death. But if you use it as a pastel tint, it is said that purple can trigger soft, romantic feelings; soothing and sedative.
The psychological effect strongly depends on how the colour is used: dark blue is connected to richness, royalty and the church, invoking feelings of calmness and sedation. However, if used indiscriminately, it can produce strong feelings of melancholia and uneasiness and can be quite depressing.
Pure green and greyed out green: coolness, tranquillity and sedation. If mixed with a bit of yellow, it probably will induce biliousness (whatever that means, it wasn't in my dictionary, but it sounds like bile and meant negatively).
At the end of the day, all colours do have positive as well as negative effects on your mood and the effect strongly depends on how you use the colours (colour contrast and harmony), the combination (colour schemes), the purity of the colour, the purpose of the room, the type of people who're going to use the area, etc. And interior designers like me can add this information to their woolly speeches :)